ACT I.
In her Paris salon, the courtesan Violetta Valéry welcomes guests to her home, among them Flora Bervoix, Marquis d’Obigny, Baron Douphol and Gastone, who introduces a new admirer, Alfredo Germont. The latter, confessing that he has adored Violetta from afar, offers a toast at her request (brindisi: "Libiamo"); she joins him in the salute to pleasure. As her guests move into the ballroom, Violetta, suddenly feeling faint, remains behind. Alfredo returns, concerned about her, and ardently declares his love ("Un dì felice"). At first, Violetta protests that love means nothing to her, but Alfredo’s sincerity touches her, and she gives him a camellia, her symbol, promising that he may return to see her when the flower has withered. After her guests have gone, Violetta wonders if Alfredo could be the man to fulfill her dream of love ("Ah, fors’è lui"). As she ponders her need for freedom ("Sempre libera"), Alfredo’s voice is heard outside, arguing in favor of romance.

ACT II.
Some months later, in a country villa near Paris, where he now lives with Violetta, Alfredo muses upon his contentment ("De’ miei bollenti spiriti"). When the maid, Annina, reveals that Violetta has been selling her jewels to pay their expenses, Alfredo departs for the city to settle their affairs at his own cost. Violetta comes looking for him and finds an invitation from Flora to a party that night. She puts it aside, having no desire to resume her former life. Alfredo’s father appears unexpectedly, demanding that Violetta renounce his son; the scandal of Alfredo’s liaison threatens his sister’s engagement ("Pura siccome un angelo"). Violetta at first refuses, but when Germont suggests that the fleeting charms of youth are her sole appeal for Alfredo, she agrees to make the sacrifice ("Dite alla giovine"). After Germont departs, Violetta sends a message accepting Flora’s invitation, then begins a farewell note to Alfredo. He enters suddenly, surprising her; hiding the note, she tearfully reaffirms her love ("Amami, Alfredo") before rushing away. Before long, a messenger brings her letter to Alfredo. Germont returns to console his despairing son with recollections of family life in Provence ("Di Provenza"). But Alfredo, seeing Flora’s invitation, concludes that Violetta has abandoned him for another lover and determines to confront her.

At her soiree, Flora learns from the Marquis that Violetta and Alfredo have parted. The floor is cleared for a band of fortunetelling Gypsies and dancers dressed as bullfighters, who sing of a matador and his coy sweetheart ("E Piquillo un bel gagliardo"). Soon Alfredo arrives, making bitter comments about love and gambling recklessly. Violetta, nervous and pale, enters on the arm of her old admirer, Baron Douphol, who proceeds to lose a small fortune to Alfredo. When the guests file into an adjoining room for supper, Violetta intercepts Alfredo, imploring him to leave before he further angers the baron. Misunderstanding her apprehension, he demands that she admit she loves Douphol. Bound by her promise to Germont, she pretends she does. Mad with jealousy, Alfredo calls the other guests as witnesses, then denounces Violetta and hurls his winnings at her feet ("Questa donna conoscete?"). As the guests rebuke him and Douphol challenges him to a duel, Germont enters and berates his son, who is stricken with remorse.

ACT III.

In Violetta’s bedroom, Dr. Grenvil tells Annina her mistress has not long to live. Tuberculosis is consuming her. When she awakens, Violetta rereads a letter from Germont telling her the baron was only wounded in his duel with Alfredo, who knows of her sacrifice and is on his way to ask her pardon. Sensing that it is too late, Violetta bids farewell to her past ("Addio del passato"). After Mardi Gras revelers pass by outside, Alfredo arrives. The lovers ecstatically plan to leave Paris forever ("Parigi, o cara"). Germont comes in with the doctor just before Violetta is seized with a last resurgence of strength. Crying out that she feels life returning, she falls dead.